CODEWITHSUNDEEP
python-3.x
Nicholas DePasquale
Nicholas DePasquale

Reputation: 27

Creating a function that creates two lists in Python 3

I am trying to create a function, getStocks, that gets from the user two lists, one containing the list of stock names and the second containing the list of stock prices. This should be done in a loop such that it keeps on getting a stock name and price until the user enters the string 'done' as a stock name. The function should return both lists. My main issues are figuring out what my parameters are, how to continuously take in the name and price, and what type of loop I should be using. I am very new to programming so any help would be appreciated. I believe I'm close but I am unsure where my errors are.

def getStocks(name,price):
    stockNames = []
    stockPrices = []
    i = 0
    name = str(input("What is the name of the stock?"))
    price = int(input("what is the price of that stock?"))
    while i < len(stockNames):
        stockNames.append(name)
        stockPrices.append(price)
        i += 1
    else:
        if name = done
    return stockNames
    return stockPrices

Upvotes: 0

Views: 1771

Answers (1)

user3126264
user3126264

Reputation:

Your question is a bit unclear but some things off the bat, you cant have two return lines, once you hit the first, it leaves the function. Instead you'do write something like

return (stockNames, stockPrices)

Secondly while loops dont have an else, so you'd actually set up your while loop, then setup an if statement at the beginning to check if the string is 'done', then act accordingly. Break will get you out of your last while loop, even though it looks like it's associated with the if. So something like this:

while i < len(stockNames):
    if name.upper() == 'DONE':
        break
    else:
        stockNames.append(name)
        stockPrices.append(price)
        i += 1

Also you have to use == (comparison) instead of = (assignment) when you check your name = done. And dont forget done is a string, so it needs to be in quotations, and I used .upper() to make the input all caps to cover if its lower case or uppercase.

If you can clear up your question a little bit, I can update this answer to include everything put together. I'm not quite understanding why you want to input a list and then also take user input, unless you're appending to that list, at which point you'd want to put the whole thing in a while loop maybe.

Update:

Based on your comment, you could do something like this and enclose the whole thing in a while loop. This takes the incoming two lists (assuming you made a master list somewhere) and sends them both into the getStocks function, where someone can keep appending to the pre-existing list, and then when they type done or DONE or DoNe (doesn't matter since you use .upper() to make the input capitalized) you break out of your while loop and return the updated lists:

def getStocks(name, price):
    stockNames = name
    stockPrices = price

    while 1:
        inputName = str(input("What is the name of the stock?"))
        inputPrice = int(input("what is the price of that stock?"))

        if name.upper() != 'DONE':
            stockNames.append(inputName)
            stockPrices.append(inputPrice)
        else:
            break

    return (stockNames, stockPrices)

But really, depending on the rest of the structure, you might want to make a dictionary instead of having 2 separate lists, that way everything stays in key:value pairs, so instead of having to check index 0 on both and hoping they didn't get shifted by some rogue function, you'd have the key:value pair of "stock_x":48 always together.

Upvotes: 0

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